<!DOCTYPE html>
<html>

	<head>
		<meta charset="UTF-8">
		<title></title>
	</head>

	<body>
		<select>
			<option value="红色">红色</option>
			<option value="绿色">绿色</option>
			<option value="蓝色">蓝色</option>
		</select>
		<script>
			document.getElementsByTagName("option")(1).selected = true
		</script>
	</body>

</html>